Migrating the Dispatcher configuration from AMS to AEM as a Cloud Service

Main Differences between AMS Dispatcher and AEM as a Cloud Service

The Apache and Dispatcher configuration in AEM as a Cloud Service is quite similar to the AMS one. The main differences are:

  • In AEM as a Cloud Service, some Apache directives may not be used (for example Listen or LogLevel)
  • In AEM as a Cloud Service, only some pieces of the Dispatcher configuration can be put in include files and their naming is important. For example, filter rules that you want to reuse across different hosts must be put in a file called filters/filters.any. See the reference page for more information.
  • In AEM as a Cloud Service there is extra validation to disallow filter rules written using /glob to prevent security issues. Since deny * will be used rather than allow * (which cannot be used), customers will benefit from running the Dispatcher locally and doing trial and error, looking at the logs to know exactly what paths the Dispatcher filters are blocking in order for those can be added.

Guidelines for migrating dispatcher configuration from AMS to AEM as a Cloud Service

The Dispatcher configuration structure has differences between Managed Services and AEM as a Cloud Service. Presented below, is a step by step guide on how to migrate from AMS Dispatcher configuration version 2 to AEM as a Cloud Service.

How to convert an AMS to an AEM as a Cloud service Dispatcher configuration

The following section provides a step-by-step instructions on how to convert an AMS configuration. It assumes
that you have an archive with a structure similar to the one described in Cloud Manager Dispatcher configuration

Extract the archive and remove an eventual prefix

Extract the archive to a folder, and make sure the immediate subfolders start with conf, conf.d,
conf.dispatcher.d and conf.modules.d. If they don’t, move them up in the hierarchy.

Get rid of unused subfolders and files

Remove subfolders conf and conf.modules.d, as well as files matching conf.d/*.conf.

Get rid of all non-publish virtual hosts

Remove any virtual host file in conf.d/enabled_vhosts that has author, unhealthy, health,
lc or flush in its name. All virtual host files in conf.d/available_vhosts that are not
linked to can be removed as well.

Remove or comment virtual host sections that do not refer to port 80

If you still have sections in your virtual host files that exclusively refer to other ports than port 80, for example:

<VirtualHost *:443>
...
</VirtualHost>

remove or comment them. Statements in these sections will not get processed, but if you
keep them around, you might still end up editing them with no effect, which is confusing.

Check rewrites

Enter directory conf.d/rewrites.

Remove any file named base_rewrite.rules and xforwarded_forcessl_rewrite.rules and remember to
remove Include statements in the virtual host files referring to them.

If conf.d/rewrites now contains a single file, it should be renamed to rewrite.rules and don’t
forget to adapt the Include statements referring to that file in the virtual host files as well.

If the folder however contains multiple, virtual host-specific files, their contents should be
copied to the Include statement referring to them in the virtual host files.

Check variables

Enter directory conf.d/variables.

Remove any file named ams_default.vars and remember to remove Include statements in the virtual
host files referring to them.

If conf.d/variables now contains a single file, it should be renamed to custom.vars and don’t
forget to adapt the Include statements referring to that file in the virtual host files as well.

If the folder however contains multiple, virtual host-specific files, their contents should be
copied to the Include statement referring to them in the virtual host files.

Remove allowlists

Remove the folder conf.d/whitelists and remove Include statements in the virtual host files referring to
some file in that subfolder.

Replace any variable that is no longer available

In all virtual host files:

Rename PUBLISH_DOCROOT to DOCROOT
Remove sections referring to variables named DISP_ID, PUBLISH_FORCE_SSL or PUBLISH_WHITELIST_ENABLED

Check your state by running the validator

Run the Dispatcher validator in your directory, with the httpd subcommand:

$ validator httpd .

If you see errors about missing include files, check whether you correctly renamed those
files.

If you see Apache directives that are not allowlisted, remove them.

Get rid of all non-publish farms

Remove any farm file in conf.dispatcher.d/enabled_farms that has author, unhealthy, health,
lc or flush in its name. All farm files in conf.dispatcher.d/available_farms that are not
linked to can be removed as well.

Rename farm files

All farms in conf.d/enabled_farms must be renamed to match the pattern *.farm, so e.g. a
farm file called customerX_farm.any should be renamed customerX.farm.

Check cache

Enter directory conf.dispatcher.d/cache.

Remove any file prefixed ams_.

If conf.dispatcher.d/cache is now empty, copy the file conf.dispatcher.d/cache/rules.any
from the standard Dispatcher configuration to this folder. The standard Dispatcher
configuration can be found in the folder src of this SDK. Don’t forget to adapt the
$include statements referring to the ams_*_cache.any rule files in the farm files
as well.

If instead conf.dispatcher.d/cache now contains a single file with suffix _cache.any,
it should be renamed to rules.any and don’t forget to adapt the $include statements
referring to that file in the farm files as well.

If the folder however contains multiple, farm-specific files with that pattern, their contents
should be copied to the $include statement referring to them in the farm files.

Remove any file that has the suffix _invalidate_allowed.any.

Copy the file conf.dispatcher.d/cache/default_invalidate_any from the default
AEM in the Cloud Dispatcher configuration to that location.

In each farm file, remove any contents in the cache/allowedClients section and replace it
with:

$include "../cache/default_invalidate.any"

Check client headers

Enter directory conf.dispatcher.d/clientheaders.

Remove any file prefixed ams_.

If conf.dispatcher.d/clientheaders now contains a single file with suffix _clientheaders.any,
it should be renamed to clientheaders.any and don’t forget to adapt the $include statements
referring to that file in the farm files as well.

If the folder however contains multiple, farm-specific files with that pattern, their contents
should be copied to the $include statement referring to them in the farm files.

Copy the file conf.dispatcher/clientheaders/default_clientheaders.any from the default
AEM as a Cloud Service Dispatcher configuration to that location.

In each farm file, replace any clientheader include statement that looks as follows:

$include "/etc/httpd/conf.dispatcher.d/clientheaders/ams_publish_clientheaders.any"
$include "/etc/httpd/conf.dispatcher.d/clientheaders/ams_common_clientheaders.any"

with the statement:

$include "../clientheaders/default_clientheaders.any"

Check filter

Enter directory conf.dispatcher.d/filters.

Remove any file prefixed ams_.

If conf.dispatcher.d/filters now contains a single file it should be renamed to
filters.any and don’t forget to adapt the $include statements referring to that
file in the farm files as well.

If the folder however contains multiple, farm-specific files with that pattern, their contents
should be copied to the $include statement referring to them in the farm files.

Copy the file conf.dispatcher/filters/default_filters.any from the default
AEM as a Cloud Service Dispatcher configuration to that location.

In each farm file, replace any filter include statements that look as follows:

$include "/etc/httpd/conf.dispatcher.d/filters/ams_publish_filters.any"

with the statement:

$include "../filters/default_filters.any"

Check renders

Enter directory conf.dispatcher.d/renders.

Remove all files in that folder.

Copy the file conf.dispatcher.d/renders/default_renders.any from the default
AEM as a Cloud Service Dispatcher configuration to that location.

In each farm file, remove any contents in the renders section and replace it
with:

$include "../renders/default_renders.any"

Check virtualhosts

Rename the directory conf.dispatcher.d/vhosts to conf.dispatcher.d/virtualhosts and enter it.

Remove any file prefixed ams_.

If conf.dispatcher.d/virtualhosts now contains a single file it should be renamed to
virtualhosts.any and don’t forget to adapt the $include statements referring to that
file in the farm files as well.

If the folder however contains multiple, farm-specific files with that pattern, their contents
should be copied to the $include statement referring to them in the farm files.

Copy the file conf.dispatcher/virtualhosts/default_virtualhosts.any from the default
AEM as a Cloud Service Dispatcher configuration to that location.

In each farm file, replace any filter include statements that look as follows:

$include "/etc/httpd/conf.dispatcher.d/vhosts/ams_publish_vhosts.any"

with the statement:

$include "../virtualhosts/default_virtualhosts.any"

Check your state by running the validator

Run the AEM as a Cloud Service Dispatcher validator in your directory, with the dispatcher subcommand:

$ validator dispatcher .

If you see errors about missing include files, check whether you correctly renamed those
files.

If you see errors concerning undefined variable PUBLISH_DOCROOT, rename it to DOCROOT.

For every other error, see the Troubleshooting section of the
validator tool documentation.

Test your configuration with a local deployment (requires Docker installation)

Using the script docker_run.sh in the AEM as a Cloud Service Dispatcher Tools, you can test that
your configuration does not contain any other error that would only show up in
deployment:

Step 1: Generate deployment information with the validator

validator full -d out .

This validates the full configuration and generates deployment information in out

Step 2: Start the Dispatcher in a docker image with that deployment information

With your AEM publish server running on your macOS computer, listening on port 4503,
you can run start the Dispatcher in front of that server as follows:

$ docker_run.sh out docker.for.mac.localhost:4503 8080

This will start the container and expose Apache on local port 8080.

Use your new Dispatcher configuration

Congratulations! If the validator no longer reports any issue and the
docker container starts up without any failures or warnings, you’re
ready to move your configuration to a dispatcher/src subdirectory
of your git repository.

Customers who are using AMS Dispatcher configuration version 1 should contact customer support to help them migrate from version 1 to version 2 so the instructions above can be followed.

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